LoongArch: Add memory management

Add memory management support for LoongArch, including: cache and tlb
management, page fault handling and ioremap/mmap support.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 165 insertions, 0 deletions

diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
new file mode 100644
index 000000000000..afd6634ce171
--- /dev/null
+++ b/arch/loongarch/mm/init.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/pagemap.h>
+#include <linux/memblock.h>
+#include <linux/memremap.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/highmem.h>
+#include <linux/swap.h>
+#include <linux/proc_fs.h>
+#include <linux/pfn.h>
+#include <linux/hardirq.h>
+#include <linux/gfp.h>
+#include <linux/initrd.h>
+#include <linux/mmzone.h>
+
+#include <asm/asm-offsets.h>
+#include <asm/bootinfo.h>
+#include <asm/cpu.h>
+#include <asm/dma.h>
+#include <asm/mmu_context.h>
+#include <asm/sections.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
+
+/*
+ * We have up to 8 empty zeroed pages so we can map one of the right colour
+ * when needed.	 Since page is never written to after the initialization we
+ * don't have to care about aliases on other CPUs.
+ */
+unsigned long empty_zero_page, zero_page_mask;
+EXPORT_SYMBOL_GPL(empty_zero_page);
+EXPORT_SYMBOL(zero_page_mask);
+
+void setup_zero_pages(void)
+{
+	unsigned int order, i;
+	struct page *page;
+
+	order = 0;
+
+	empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
+	if (!empty_zero_page)
+		panic("Oh boy, that early out of memory?");
+
+	page = virt_to_page((void *)empty_zero_page);
+	split_page(page, order);
+	for (i = 0; i < (1 << order); i++, page++)
+		mark_page_reserved(page);
+
+	zero_page_mask = ((PAGE_SIZE << order) - 1) & PAGE_MASK;
+}
+
+void copy_user_highpage(struct page *to, struct page *from,
+	unsigned long vaddr, struct vm_area_struct *vma)
+{
+	void *vfrom, *vto;
+
+	vto = kmap_atomic(to);
+	vfrom = kmap_atomic(from);
+	copy_page(vto, vfrom);
+	kunmap_atomic(vfrom);
+	kunmap_atomic(vto);
+	/* Make sure this page is cleared on other CPU's too before using it */
+	smp_wmb();
+}
+
+int __ref page_is_ram(unsigned long pfn)
+{
+	unsigned long addr = PFN_PHYS(pfn);
+
+	return memblock_is_memory(addr) && !memblock_is_reserved(addr);
+}
+
+void __init paging_init(void)
+{
+	unsigned long max_zone_pfns[MAX_NR_ZONES];
+
+#ifdef CONFIG_ZONE_DMA
+	max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	max_zone_pfns[ZONE_DMA32] = MAX_DMA32_PFN;
+#endif
+	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
+
+	free_area_init(max_zone_pfns);
+}
+
+void __init mem_init(void)
+{
+	max_mapnr = max_low_pfn;
+	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
+
+	memblock_free_all();
+	setup_zero_pages();	/* Setup zeroed pages.  */
+}
+
+void __ref free_initmem(void)
+{
+	free_initmem_default(POISON_FREE_INITMEM);
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	int ret;
+
+	ret = __add_pages(nid, start_pfn, nr_pages, params);
+
+	if (ret)
+		pr_warn("%s: Problem encountered in __add_pages() as ret=%d\n",
+				__func__,  ret);
+
+	return ret;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	struct page *page = pfn_to_page(start_pfn);
+
+	/* With altmap the first mapped page is offset from @start */
+	if (altmap)
+		page += vmem_altmap_offset(altmap);
+	__remove_pages(start_pfn, nr_pages, altmap);
+}
+#endif
+#endif
+
+/*
+ * Align swapper_pg_dir in to 64K, allows its address to be loaded
+ * with a single LUI instruction in the TLB handlers.  If we used
+ * __aligned(64K), its size would get rounded up to the alignment
+ * size, and waste space.  So we place it in its own section and align
+ * it in the linker script.
+ */
+pgd_t swapper_pg_dir[_PTRS_PER_PGD] __section(".bss..swapper_pg_dir");
+
+pgd_t invalid_pg_dir[_PTRS_PER_PGD] __page_aligned_bss;
+#ifndef __PAGETABLE_PUD_FOLDED
+pud_t invalid_pud_table[PTRS_PER_PUD] __page_aligned_bss;
+#endif
+#ifndef __PAGETABLE_PMD_FOLDED
+pmd_t invalid_pmd_table[PTRS_PER_PMD] __page_aligned_bss;
+EXPORT_SYMBOL_GPL(invalid_pmd_table);
+#endif
+pte_t invalid_pte_table[PTRS_PER_PTE] __page_aligned_bss;
+EXPORT_SYMBOL(invalid_pte_table);